Zinc-coated steel cord with improved fatigue resistance

Abstract

A steel cord for the reinforcement of thermoplastic elastomers, the steel cord including more than one strand, each strand including two or more steel filaments, at least some of said the steel filaments being provided with a zinc coating. The zinc coating has a thickness lower than two micrometer and an alloy layer zinc-steel is present between the zinc coating and the steel.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a steel cord adapted for the reinforcement of thermoplastic elastomers and to a composite. The composite comprises a thermoplastic elastomer such as polyurethane as matrix and the steel cords as reinforcing material. The steel cord is a multi-strand steel cord, i.e. a steel cord comprising more than one strand.BACKGROUND OF THE INVENTION[0002]Steel cords are widely known to reinforce rubber products such as tires and conveyor belts. To a lesser extent, steel cords are also known to reinforce thermoplastic elastomers such as polyurethanes. The adhesion mechanism between the steel cords and the rubber products is substantially different from the adhesion mechanism between steel cords and thermoplastic elastomers. The adhesion between steel cords and rubber is mainly a chemical adhesion based on the bonds created during vulcanization between a conventional copper alloy coating on the steel cord and the rubber. Although chemic...

AI Technical Summary

Benefits of technology

"The invention provides a steel cord with a coating that has both acceptable fatigue resistance and corrosion resistance. The steel cord is a multi-strand steel cord with each strand comprising two or more steel filaments, at least some of which are provided with a zinc coating. The thin zinc coating reduces the production of zinc dust and improves mechanical anchoring in the thermoplastic elastomer. The presence of a transition alloy layer zinc-steel between the steel and the zinc increases the corrosion resistance of the steel filaments and adhesion between the zinc coating and the steel. The cord core can be a core strand with two or more filaments or a plastic material of the same type and nature of the thermoplastic elastomer. The invention also relates to a composite reinforced by a steel cord as described hereabove, such as a grooved belt with polyurethane as matrix."

Problems solved by technology

Such a zinc coating, however, has its drawbacks.

A first drawback is that a suitable level of corrosion resistance is difficult to combine with an acceptable level of fatigue resistance.

Indeed increasing the thickness of the zinc coating leads to an increase of the corrosion resistance, which is an advantage, and to a decrease in fatigue resistance, which is a disadvantage, and vice versa.

A second drawback is that a zinc coating creates a lot of zinc dust and zinc particles during the downstream working of the zinc coated filaments such as the cold drawing and the twisting into the strands and cord.

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